Assessment of Radiation Exposure of Astronauts in Space

Draft document: Assessment of Radiation Exposure of Astronauts in Space
Submitted by Michael Hajek, Vienna University of Technology; Austrian Radiation Protection Association
Commenting as an individual

Assessment of Radiation Exposure of Astronauts in Space
Draft report for consultation
ICRP ref 4819-7515-1888 

The efforts undertaken by the International Commission on Radiological Protection (ICRP) in publishing a draft report regarding the exposure of astronauts through cosmic radiation are highly acknowledged. This report fills the missing gap that has arisen from the fact that astronauts had not been classified as being occupationally exposed in the sense of the ICRP system for radiation protection.

The draft report compiles and reviews in detail the space radiation environment, radiation-related quantities and units, terminology as well as methods of measurement to assess the radiation exposure of astronauts. Comparatively little space, however, is devoted to providing guidance on identifying and solving pending physiological and technological issues in order to enable definition of reference values for risks or doses. It is acknowledged that the current understanding of radiobiological action of heavy ions is far from being complete and in most instances such reference values would have to be mission-specific. However, astronaut exposure in my view still should be treated as a planned rather than an emergency exposure situation as defined by ICRP Publication 103.

Of some points that I believe would require amendment, only those considered most important shall be addressed here:

A couple of figures obviously contain misleading captions or added legends, where the symbols (due to font incompatibilities) do not coincide with those used in the plots. At several occasions, outdated figures are presented (e.g., Fig. 4.4 illustrating thermoluminescence detector response to charged particles), where more recent, complete and informative data would have been available from other publications. The bibliography thus appears to be incomplete, ignoring some of the most cited publications in the field.

While a separate chapter is dedicated to inter-comparison and validation of radiation transport codes, nothing similar can be found for radiation detectors, where the ICCHIBAN programme (which is mentioned in brackets on p. 78) without doubt marks one of the most important break-throughs in the development of space dosimetry.

The importance of improving the predictive capability of solar-particle event models is only mentioned in passing.